1. Field of Invention
The present invention in general relates to 3′-hydroxy pterostilbene (3′-HPT). More specifically, the present invention relates to the synthesis of 3′-hydroxy pterostilbene.
2. Description of Prior Art
The medical significance of 3′-hydroxy pterostilbene as an apoptosis inducing agent as compared to trans-resveratrol and piceatannol is well documented (M. Tolomeo et al./The International Journal of Biochemistry & Cell Biology 37 (2005) 1709-1726). 3′-HPT has also been documented to be a more potent anti-cancer agent than pterostilbene (PLoS ONE 9(11), 2014, e111814).
Synthetic schemes for 3′-hydroxy pterostilbene with low yields have also been documented in prior art. The important ones are,                A. Wittig Reaction based synthesis of 4-[2-(3,5-Dimethoxyphenyl)ethenyl]-1,2-benzenediol (3′-hydroxy pterostilbene) with an overall yield of 33% (Somepalli VENKATESHWARULU et al in Biosci. Biotechnol. Biochem., 67 (11), 2463-2466, 2003). In this prior art reference, several technical disadvantages are noted.        a) The Wittig condensation uses n-butyl lithium which is very difficult to handle in industrial synthetic schemes;        b) The Wittig condensation also produces cis and trans forms of the stilbenes and it is only the trans form that may be effectively de-benzylated to form 3′-hydroxy pterostilbene. Obtaining the trans stilbene by column chromatography has been contemplated. However, this is not feasible in industrial production. Further, the conversion of cis to trans stilbene uses iodine which is very expensive to use in an industrial scale and the conversion could again produce both cis and trans stilbenes.        B. The condensation of 3,5-dimethoxyphosphonium bromide with 3′,4′-di(tert-butyldimethylsilyloxy)benzaldehyde to get a mixture of cis and trans stilbenes and followed by the deprotection of isomeric forms to yield 25% 3′-hydroxy pterostilbene (Journal of Medicinal Chemistry, 2003, 46, 3646-3554). In this prior art, the technical disadvantages include,                    a) The starting reactant 3′,4′-di(tert-butyldimethylsilyloxy)benzaldehyde represents a bulky group to handle in an industrial set up; and            b) The formation of cis and trans isomers of the stilbene reduces the yield of desired trans isomer.                        
Alternatives to the aforementioned low yield and industrially non-feasible technical processes for the synthesis of 3′-hydroxy pterostilbene form the primary objective of the present invention. Accordingly, it is the primary objective of the present invention is disclose a industrially viable, high yielding synthetic scheme for 3′-hydroxy pterostilbene. The present invention fulfills this objective and provided further related advantages.